7,838 research outputs found
Boost invariant quantum evolution of a meson field at large proper times
We construct asymptotic solutions of the functional Schroedinger equation for
a scalar field in the Gaussian approximation at large proper time. These
solutions describe the late proper time stages of the expansion of a meson gas
with boost invariant boundary conditions. The relevance of these solutions for
the formation of a disoriented chiral condensate in ultra relativistic
collisions is discussed.Comment: 9 pages, LATE
On Haag Duality for Pure States of Quantum Spin Chain
We consider quantum spin chains and their translationally invariant pure
states. We prove Haag duality for quasilocal observables localized in
semi-infinite intervals when the von Neumann algebras generated by observables
localized in these intervals are not type I
A formula for charmonium suppression
In this work a formula for charmonium suppression obtained by Matsui in 1989
is analytically generalized for the case of complex c-cbar potential described
by a 3-dimensional and isotropic time-dependent harmonic oscillator (THO). It
is suggested that under certain conditions the formula can be applied to
describe J/\psi suppression in heavy-ion collisions at CERN-SPS, RHIC, and LHC
with the advantage of analytical tractability.Comment: 4 pages, no figures, to appear in Phys. At. Nucl., vol. 7
Kakutani Dichotomy on Free States
Two quasi-free states on a CAR or CCR algebra are shown to generate
quasi-equivalent representations unless they are disjoint.Comment: 12 page
Entanglement, Haag-duality and type properties of infinite quantum spin chains
We consider an infinite spin chain as a bipartite system consisting of the
left and right half-chain and analyze entanglement properties of pure states
with respect to this splitting. In this context we show that the amount of
entanglement contained in a given state is deeply related to the von Neumann
type of the observable algebras associated to the half-chains. Only the type I
case belongs to the usual entanglement theory which deals with density
operators on tensor product Hilbert spaces, and only in this situation
separable normal states exist. In all other cases the corresponding state is
infinitely entangled in the sense that one copy of the system in such a state
is sufficient to distill an infinite amount of maximally entangled qubit pairs.
We apply this results to the critical XY model and show that its unique ground
state provides a particular example for this type of entanglement.Comment: LaTeX2e, 34 pages, 1 figure (pstricks
Real-Space Imaging of Alternate Localization and Extension of Quasi Two-Dimensional Electronic States at Graphite Surfaces in Magnetic Fields
We measured the local density of states (LDOS) of a quasi two-dimensional
(2D) electron system near point defects on a surface of highly oriented
pyrolytic graphite (HOPG) with scanning tunneling microscopy and spectroscopy.
Differential tunnel conductance images taken at very low temperatures and in
high magnetic fields show a clear contrast between localized and extended
spatial distributions of the LDOS at the valley and peak energies of the Landau
level spectrum, respectively. The localized electronic state has a single
circular distribution around the defects with a radius comparable to the
magnetic length. The localized LDOS is in good agreement with a spatial
distribution of a calculated wave function for a single electron in 2D in a
Coulomb potential in magnetic fields.Comment: 4 pages, 4 figure
Four-dimensional lattice chiral gauge theories with anomalous fermion content
In continuum field theory, it has been discussed that chiral gauge theories
with Weyl fermions in anomalous gauge representations (anomalous gauge
theories) can consistently be quantized, provided that some of gauge bosons are
permitted to acquire mass. Such theories in four dimensions are inevitablly
non-renormalizable and must be regarded as a low-energy effective theory with a
finite ultraviolet (UV) cutoff. In this paper, we present a lattice framework
which enables one to study such theories in a non-perturbative level. By
introducing bare mass terms of gauge bosons that impose ``smoothness'' on the
link field, we explicitly construct a consistent fermion integration measure in
a lattice formulation based on the Ginsparg-Wilson (GW) relation. This
framework may be used to determine in a non-perturbative level an upper bound
on the UV cutoff in low-energy effective theories with anomalous fermion
content. By further introducing the St\"uckelberg or Wess-Zumino (WZ) scalar
field, this framework provides also a lattice definition of a non-linear sigma
model with the Wess-Zumino-Witten (WZW) term.Comment: 18 pages, the final version to appear in JHE
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